In this Letter, we demonstrate a mode-locked Er-doped fiber laser incorporating antimony telluride (Sb{sub 2}Te{sub 3}) topological insulator (TI) as a saturable absorber (SA). The laser was capable of generating 270 fs-short soliton pulses at 1560 nm wavelength, which are the shortest solitons generated with a TI-based saturable absorber so far. In order to form a saturable absorber, a bulk piece of Sb{sub 2}Te{sub 3} was deposited on a side-polished single-mode fiber with the presence of a low refractive index polymer. Such saturable absorber exhibits modulation depth at the level of 6% with less than 3 dB of non-saturable losses. Our studymore » shows that TI-based saturable absorbers with evanescent field interaction might compete with SAs based on carbon nanomaterials, like graphene or nanotubes. Additionally, thanks to the interaction with the evanescent field, the material is not exposed to high optical power, which allows to avoid optical or thermal damage.« less

The results of an analytical description and of a particle-in-cell simulation of the interaction of an ultrashort, relativistically intense laser pulse, obliquely incident on a nonuniform overdense plasma, are presented and several novel features are identified. The absorption and reflection of the ultraintense electromagnetic laser radiation from a sharp-boundary plasma, high harmonic generation, and the transformation into low-frequency radiation are discussed. In the case of weak plasma nonuniformity the excitation of nonlinear Langmuir oscillations in the plasma resonance region and the resulting electron acceleration are investigated. The vacuum heating of the electrons and the self-intersection of the electron trajectories aremore » also studied. In the case of a sharp-boundary plasma, part of the energy of the laser pulse is found to be converted into a localized, relativistically strong, nonlinear electromagnetic pulse propagating into the plasma. The expansion of the hot electron cloud into the vacuum region and the action of the ponderomotive force of the laser pulse in the localized longitudinal electric field of the Langmuir oscillations lead to ion acceleration. The energy increase of a minority population of multicharged ions is found to be much greater than that of the ambient ions.« less

The results of analytical treatment and computer simulation of the interaction between the relativistically strong electromagnetic field of an ultrashort laser pulse and a highly inhomogeneous overdense plasma are presented. {open_quotes}Vacuum heating of electrons,{close_quotes} i.e., formation of a cloud of fast electrons that is expanding into vacuum is the primary mechanism responsible for electromagnetic energy absorption under the oblique incidence of an electromagnetic wave upon dense plasma with a sharp boundary. It is shown that, in the electron cloud expanding into vacuum, ions are accelerated up to the energies corresponding to the equality of ion and fast electron velocities. 30more » refs., 6 figs.« less

A simulation code is developed for the investigation of the interaction of subpicosecond high-power laser pulses with dense plasma. The heating process is studied by solving the Vlasov-Fokker-Planck equation for the electron distribution function. The skin layer of the plasma has an anisotropic non-Maxwellian electron distribution, which may be reason for the plasma turbulence and a suppression of energy losses. Hydrodynamic simulations with radiation transport are conducted to study X-ray emission and plasma relaxation. (AIP) {copyright} 1994 {ital American} {ital Institute} {ital of} {ital Physics}

The nonlinear, relativistic dynamics that results when intense (10{sup 18} W/cm{sup 2} and above) and ultrashort (one plasma period or shorter) laser pulse travels through a cold underdense plasma is investigated. Using a Lagrangian analysis of the plasma response, it can be demonstrated that the nonlinear wake, the collective dissipation, the nonlinear Compton losses, and the harmonic generation, are all determined by a finite set of integrated scalar quantities. This result holds for one-dimensional, short pulses of arbitrary amplitude, shape, and polarization, so that these very short intense laser pulses in a plasma can be viewed essentially as a quasiparticlemore » characterized by a small set of global parameters.« less